What does the "rule of thumb" for high voltage holiday detectors specify?

The "rule of thumb" for high voltage holiday detectors specifies 100 Volts per mil. This guideline is widely recognized in the coatings industry to help ensure effective detection of holidays or discontinuities in protective coatings applied to surfaces such as metal.

The rationale behind this value is grounded in achieving a balance between sensitivity and safety during the inspection process. At 100 Volts per mil, the voltage is sufficient to detect even minor flaws in the coating without risking damage to the surface or the coating itself. This voltage level is practical for most standard coatings and offers a reliable method of ensuring that protective measures are intact.

Higher voltage values, while potentially offering heightened sensitivity, can lead to risks of damaging thin coatings or the substrate beneath, making 100 Volts per mil a sensible choice for various applications within the industry.